Groucho Marx in his extremely popular 1950's television series "You Bet Your Life", which aired on the NBC Television Network. The "secret word" in this episode is "Chair". The series was a comedic game show which allowed plenty of room for Groucho's verbal comedy. Contains original broadcast commercials.
You know, this episode sorta proves a lot of Internet Archives reviewers to be very wrong, if not outright liars. Groucho would be pleased.
Of course, this isn't Groucho at his best, but he is well-suited to the medium of television and proves to be a very pleasing personality, and completely able to be humorous without an actual script (Groucho would generally plan a few ideas for each episode, but there was no actual script in the usual sense).